- Rhodium-Catalyzed Deoxygenation and Borylation of Ketones: A Combined Experimental and Theoretical Investigation
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The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.
- Tao, Lei,Guo, Xueying,Li, Jie,Li, Ruoling,Lin, Zhenyang,Zhao, Wanxiang
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supporting information
p. 18118 - 18127
(2020/11/26)
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- Nickel-Mediated Trifluoromethylation of Phenol Derivatives by Aryl C?O Bond Activation
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The increasing pharmaceutical importance of trifluoromethylarenes has stimulated the development of more efficient trifluoromethylation reactions. Tremendous efforts have focused on copper- and palladium-mediated/catalyzed trifluoromethylation of aryl halides. In contrast, no general method exists for the conversion of widely available inert electrophiles, such as phenol derivatives, into the corresponding trifluoromethylated arenes. Reported herein is a practical nickel-mediated trifluoromethylation of phenol derivatives with readily available trimethyl(trifluoromethyl)silane (TMSCF3). The strategy relies on PMe3-promoted oxidative addition and transmetalation, and CCl3CN-induced reductive elimination. The broad utility of this transformation has been demonstrated through the direct incorporation of trifluoromethyl into aromatic and heteroaromatic systems, including biorelevant compounds.
- Hu, Wei-Qiang,Pan, Shen,Qing, Feng-Ling,Vicic, David A.,Xu, Xiu-Hua
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supporting information
p. 16076 - 16082
(2020/07/04)
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- General Paradigm in Photoredox Nickel-Catalyzed Cross-Coupling Allows for Light-Free Access to Reactivity
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Self-sustained NiI/III cycles are established as a potentially general paradigm in photoredox Ni-catalyzed carbon–heteroatom cross-coupling reactions through a strategy that allows us to recapitulate photoredox-like reactivity in the absence of light across a wide range of substrates in the amination, etherification, and esterification of aryl bromides, the latter of which has remained, hitherto, elusive under thermal Ni catalysis. Moreover, the accessibility of esterification in the absence of light is especially notable because previous mechanistic studies on this transformation under photoredox conditions have unanimously invoked energy-transfer-mediated pathways.
- Nocera, Daniel G.,Qin, Yangzhong,Sun, Rui
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supporting information
p. 9527 - 9533
(2020/04/08)
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- Efficient and selective hydrogenation of C-O bonds with a simple sodium formate catalyzed by nickel
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A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.
- Xi, Xiaoxiang,Chen, Tieqiao,Zhang, Ji-Shu,Han, Li-Biao
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supporting information
p. 1521 - 1524
(2018/02/19)
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- TRIPHENYLETHYLENE COMPOUNDS AND USES THEREOF
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Triphenylethylene compounds as dual aromatase inhibitors and selective estrogen receptors modulators are described. Also described are methods for treating patients of breast cancers, and patients of breast cancer comorbid with osteoporosis, using the des
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Paragraph 0108
(2017/06/19)
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- Nickel-Catalyzed Phosphorylation of Phenol Derivatives via C-O/P-H Cross-Coupling
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An efficient nickel-catalyzed phosphorylation of phenol derivatives with P(O)-H compounds via C-O/P-H cross-coupling is described. Under the reaction conditions, various phenyl pivalates coupled readily with hydrogen phosphoryl compounds to afford the corresponding coupling products aryl phosphonates and aryl phosphine oxides in good to high yields.
- Yang, Jia,Xiao, Jing,Chen, Tieqiao,Han, Li-Biao
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p. 3911 - 3916
(2016/05/24)
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- Synthesis of Triphenylethylene Bisphenols as Aromatase Inhibitors That Also Modulate Estrogen Receptors
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A series of triphenylethylene bisphenol analogues of the selective estrogen receptor modulator (SERM) tamoxifen were synthesized and evaluated for their abilities to inhibit aromatase, bind to estrogen receptor α (ER-α) and estrogen receptor β (ER-β), and antagonize the activity of β-estradiol in MCF-7 human breast cancer cells. The long-range goal has been to create dual aromatase inhibitor (AI)/selective estrogen receptor modulators (SERMs). The hypothesis is that in normal tissue the estrogenic SERM activity of a dual AI/SERM could attenuate the undesired effects stemming from global estrogen depletion caused by the AI activity of a dual AI/SERM, while in breast cancer tissue the antiestrogenic SERM activity of a dual AI/SERM could act synergistically with AI activity to enhance the antiproliferative effect. The potent aromatase inhibitory activities and high ER-α and ER-β binding affinities of several of the resulting analogues, together with the facts that they antagonize β-estradiol in a functional assay in MCF-7 human breast cancer cells and they have no E/Z isomers, support their further development in order to obtain dual AI/SERM agents for breast cancer treatment.
- Lv, Wei,Liu, Jinzhong,Skaar, Todd C.,O'Neill, Elizaveta,Yu, Ge,Flockhart, David A.,Cushman, Mark
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p. 157 - 170
(2016/01/28)
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- Copper-Mediated Functionalization of Aryl Trifluoroborates
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This paper describes the Cu(OTf)2-mediated coupling of aryl and heteroaryl trifluoroborates with tetrabutylammonium or alkali metal salts to form C-O, C-N, and C-halogen bonds. The reactions proceed under mild conditions (often room temperature over 16 hours) with carboxylate, halide, and azide salts, all nucleophiles that have been underrepresented in the copper cross-coupling literature. Preliminary results show that copper salts bearing weakly coordinating X-type ligands are essential for enabling these transformations to proceed under mild conditions.
- Schimler, Sydonie D.,Sanford, Melanie S.
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supporting information
p. 2279 - 2284
(2016/10/06)
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- Comparative Study of the Limitations and Challenges in Atom-Transfer C-H Oxidations
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A comparative study is disclosed that seeks to highlight the current limitations and challenges that exist in the field of atom-transfer C-H oxidations. State-of-the-art methods are benchmarked in order to showcase clear differences and similarities. A novel Mn-mediated method for C-H oxidation is disclosed that serves as a rapid and simple method for aliphatic C-H hydroxylation. Finally, two methods that allow for C-H oxidation in the presence of pyridine-containing substrates are studied, something that is rare in the field but of great interest to the chemical community.
- Adams, Ashley M.,Du Bois,Malik, Hasnain A.
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supporting information
p. 6066 - 6069
(2016/01/09)
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- Mild and efficient nickel-catalyzed heck reactions with electron-rich olefins
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A new efficient protocol for the nickel-catalyzed Heck reaction of aryl triflates with vinyl ethers is presented. Mild reaction conditions that equal those of the corresponding palladium-catalyzed Heck reaction are applied, representing a practical and more sustainable alternative to the conventional regioselective arylation of vinyl ethers. A catalytic system comprised of Ni(COD)2 and 1,1″-bis(diphenylphosphino)ferrocene (DPPF) in combination with the tertiary amine Cy2NMe proved effective in the olefination of a wide range of aryl triflates. Both electron-deficient and electron-rich arenes proved compatible, and the corresponding aryl methyl ketone could be secured after hydrolysis in yields approaching quantitative. Good functional group tolerance was observed matching the characteristics of the analogous Pd-catalyzed Heck reaction. The high levels of catalytic activity were explained by the intermediacy of a cationic nickel(II) complex potentially responsible for the successive β-hydride elimination and base promoted catalyst regeneration. Although these elementary reactions are normally considered challenging, DFT calculations suggested this pathway to be favorable under the applied reaction conditions.
- Gogsig, Thomas M.,Kleimark, Jonatan,Nilsson Lill, Sten O.,Korsager, Signe,Lindhardt, Anders T.,Norrby, Per-Ola,Skrydstrup, Troels
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supporting information; experimental part
p. 443 - 452
(2012/03/07)
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- Kinetics and mechanism of aminolysis of phenyl acetates and phenyl trimethylacetates in dimethyl suldoxide
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Kinetic studies have been carried out on the reactions of phenyl acetates and phenyl trimethylacetates in dimethyl sulfoxide.The rate ratios between the two acyl compounds, and the positive sign and large magnitude of the cross-interaction constants, ρXZ, between substituents X in the nucleophile and Z in the leaving group are considered to favour the rate-limiting expulsion of aryl oxide from the tetrahedral intermediate T+/-.The aprotic solvent used makes the proposed mechanism with a cyclic transition state more attractive especially in view of the greater charge dispersion and assistance to leaving group departure provided in such a structure.
- Koh, Han Joong,Kim, Seung Il,Lee, Byung Choon,Lee, Ikchoon
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p. 1353 - 1358
(2007/10/03)
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